Hope This Helps.

[Somerset]

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// This program will let the operator select routines to convert  
// an octal number to decimal, a decimal number to octal, convert 
// a hex to decimal, decimal to hex, find the square root of a
// number, convert keyboard characters to decimal and octal       
// values, or add, subtract, multiply, or divide numbers.         
#include <iostream.h>

void coct_dec (),cdec_oct (),chex_dec (),cdec_hex ();
double absolute_value (double);
void sq_root (),key_value (),arith_value ();

void main ()
{
char crlf_char;
char dis_patch;
// print the menu  
loop1:  cout << "\n\n\n\n\n\n\n\n       MENU";
cout << "\n       ----";
cout << "\n\n       0 = Convert octal number to decimal.";
cout << "\n\n       1 = Convert decimal number to octal.";
cout << "\n\n       2 = Convert hex to decimal.";
cout << "\n\n       3 = Convert decimal to hex.";
cout << "\n\n       4 = Find the square root of a number.";
cout << "\n\n       5 = Convert keyboard to decimal and octal.";
cout << "\n\n       6 = Add, subtract, multiply, or divide.";
cout << "\n\n       7 = Exit program.";
// get menu selection from operator  
loop2:  cout << "\n\n       Enter menu number (0 - 7): ";
loop3:  dis_patch = cin.get ();

if (dis_patch == '\n')
goto loop3;
// now there is only six items on the menu  
if (dis_patch > '7')
{
 cout << "Input the correct menu number!";
goto loop2;
}

// get the number and dispatch to the appropriate function.  
crlf_char = cin.get (); //Get that crlf 
if (dis_patch == '0')
coct_dec ();
if (dis_patch == '1')
cdec_oct ();
if (dis_patch == '2')
chex_dec ();
if (dis_patch == '3')
cdec_hex ();
if (dis_patch == '4')
sq_root ();
if (dis_patch == '5')
key_value ();
if (dis_patch == '6')
arith_value ();

if (dis_patch == '7')
return;
else goto loop1;

}

// function to convert an octal number to decimal  
void coct_dec ()
{               
char ascii_char;
char octal_buf[11] = {'0','0','0','0','0','0','0','0','0','0','0'};
char crlf_char;
char octal_num;
int dec_count;
int index;
long int dec_value;
// prompt the operator to enter the octal number. the octal  
// characters are then stored in an a character buffer until  
// the numbers are terminated with a crlf.  
loop1:  cout << "\n\n       Enter octal number: ";
index = 0;                

do
{
++index;
ascii_char = cin.get ();
octal_buf[index] = ascii_char;
}
while (ascii_char != '\n');                
dec_count = 1;
dec_value = 0;

// we are going to figure this out in binary. mask each bit,   
// starting at the low order bit and calulate the decimal     
// number. if the bit is there, add in the decimal count for   
// that position or update the decimal count for the next      
// binary postion.                                            

do
{

--index; // trash crlf in buffer 
// mask the first binary bit of the ascii character and   
// calculate  
octal_num = octal_buf[index];
octal_num = (octal_num & 1);
if (octal_num == 1)
dec_value = (dec_value + dec_count);
dec_count = (dec_count + dec_count);
// mask the second binary bit of the ascii character and   
// calculate  
octal_num = octal_buf[index];
octal_num = (octal_num & 2);
if (octal_num == 2)
dec_value = (dec_value + dec_count);
dec_count = (dec_count + dec_count);
// mask the third binary bit of the ascii character and  
// calculate  
octal_num = octal_buf[index];
octal_num = (octal_num & 4);
if (octal_num == 4)
dec_value = (dec_value + dec_count);
dec_count = (dec_count + dec_count);

}                
// the end of the buffer contains a crlf  
while (index >= 2); //Last thing in the buffer is \n 

cout << "\n       The answer is: " << dec_value;

cout << "\n\n       Try another number 'y or n': ";
       
// if the answer is no return to menu else ask for another   
// number  
ascii_char = cin.get ();
crlf_char = cin.get (); // get that crlf  

if (ascii_char == 'n')
return;

else goto loop1;

}
// function to convert decimal to octal  
void cdec_oct ()
{
char crlf_char;
char next_digit;
char ascii_char;
int count;
long int dec_num;
int con_num[10] = {0,0,0,0,0,0,0,0,0,0};
// get the decimal number from the operator and save it in a   
// decimal value  
loop1:  cout << "\n\n       Enter decimal number: ";

cin >> dec_num;

cout << "\n       ";
cout << dec_num;               
cout << " in decimal is "; 
count= 0;

// each octal digit is the remainder of the base divided by   
// the base these are saved in a buffer for calculation to     
// an ascii character  
do
{
++count;
con_num[count] = (dec_num % 8);
dec_num = (dec_num / 8);
}               
while (dec_num != 0);

// get the digit from the buffer and make the ascii character                  

do
{
next_digit = (con_num[count] + '0');
cout << next_digit;
--count;
}
while (count != 0);
cout << " in octal.";
cout << "\n\n       Try another number (y or n): ";

crlf_char = cin.get (); // get that crlf  
ascii_char = cin.get ();
// if the answer is no return to menu else ask for another   
// number  

if (ascii_char == 'n')
return;

else goto loop1;
}
// This routine will convert a hex value to decimal  
void chex_dec ()
       
{               
char ascii_char;
char hex_buf[11] = {'0','0','0','0','0','0','0','0','0','0','0'};
char crlf_char;
int dec_count;
int index;
long int dec_value;
// prompt the operator to enter the hex number. the hex  
// characters are then stored in an a character buffer until  
// the numbers are terminated with a crlf.  
loop1:  cout << "\n\n       Enter hex number: ";
index = 0;                

do
{
++index;
ascii_char = cin.get ();
if (ascii_char <= '9')
hex_buf[index] = ascii_char - '0';
else hex_buf[index] = ((ascii_char - '0') - 7);
}
while (ascii_char != '\n');                
dec_count = 1;
dec_value = 0;

// we are going to figure this out in binary. mask each bit,   
// starting at the low order bit and calulate the decimal     
// number. if the bit is there, add in the decimal count for   
// that position or update the decimal count for the next      
// binary postion.                                            

do
{

--index; // trash crlf in buffer 
// get the ascii character out of the buffer and   
// calculate  
if (hex_buf[index] != 0)
dec_value = (dec_value + (hex_buf[index] * dec_count));
dec_count = (dec_count * 16);

}                
// the end of the buffer contains a crlf  
while (index >= 2); //Last thing in the buffer is \n 

cout << "\n       The answer is: " << dec_value;

cout << "\n\n       Try another number 'y or n': ";
       
// if the answer is no return to menu else ask for another   
// number  
ascii_char = cin.get ();
crlf_char = cin.get (); // get that crlf  

if (ascii_char == 'n')
return;

else goto loop1;

}
// function to convert decimal to hex  
void cdec_hex ()
{
char crlf_char;
char next_digit;
char ascii_char;
int count;
long int dec_num;
int con_num[10] = {0,0,0,0,0,0,0,0,0,0};
// get the decimal number from the operator and save it in a   
// decimal value  
loop1:  cout << "\n\n       Enter decimal number: ";

cin >> dec_num;

cout << "\n       ";
cout << dec_num;               
cout << " in decimal is "; 
count= 0;

// each octal digit is the remainder of the base divided by   
//the base these are saved in a buffer for calculation to     
// an ascii character  
do
{
++count;
con_num[count] = (dec_num % 16);
dec_num = (dec_num / 16);
}               
while (dec_num != 0);

// get the digit from the buffer and make the ascii character                  

do
{
if (con_num[count] > 9)
next_digit = (con_num[count] + '0' + 7);
else
next_digit = (con_num[count] + '0');

cout << next_digit;
--count;
}
while (count != 0);
cout << " in hex.";
cout << "\n\n       Try another number (y or n): ";

crlf_char = cin.get (); // get that crlf  
ascii_char = cin.get ();
// if the answer is no return to menu else ask for another   
// number  

if (ascii_char == 'n')
return;

else goto loop1;
}
// calculate the absolute value of a decimal number. if the   
// number is less than 0 then negate the number.             
double absolute_value(float func1,float func2,float func3)
{
double func_num;
func_num = (func1 * func2 - func3);
if (func_num < 0)
func_num = -func_num;
func_num = func_num;
return (func_num);
}
// function to find the square root of a number  
void sq_root ()
{
char ascii_char;
char crlf_char;
int index;
double epsilon;
float guess;
float dec_num;
// get the decimal number from the operator and save it.  
// if guess squared minus the number is greater than or    
// equal to one then thats the number else set guess to    
// the nmuber divided by guess divided by 2 guess again.  
loop1:  guess = 1.0;     // initialize some variables  
epsilon = .00001;
index = 0;
cout << "\n\n       Input decimal number: ";

cin >> dec_num;

if (dec_num < 0)
{
cout << "Cannot square root a negative number";
goto loop1;
}
   while ((absolute_value(guess,guess,dec_num) >= epsilon) && (index <= 20))
{
guess = (((dec_num / guess) + guess) / 2.0);
index = index + 1;
}
 
cout << "\n       Square root is: " << guess;
cout << "\n\n       Try another number (y or n): ";

crlf_char = cin.get (); // get that crlf  
ascii_char = cin.get ();
// if the answer is no then return to menu else ask for next   
// number  
if (ascii_char == 'n')
return;

else goto loop1;
}
// function to convert a keyboard character to its octal
// and then decimal value.  
void key_value ()
{
char ascii_char;
char crlf_char;
char next_digit;
int count;
int oct_num;
int dec_num;
int dec_count;
int con_num[4] = {0,0,0,0};
// prompt the operator for the keyboard character  
loop1:  for (count = 0; count <= 3; ++count)
con_num[count] = 0;
cout << "\n\n       Enter the Keyboard Character: ";

ascii_char = cin.get ();
crlf_char = cin.get (); // get that crlf  
// convert keyboard character to decimal and let it print  
cout << "\n\n       Keyboard Character:  '";
cout << ascii_char;
cout << "'  ";
cout << "is  "; 
 
       //convert character to octal
count = 0;
do
{
++count;
con_num[count] = (ascii_char % 8);
ascii_char = (ascii_char / 8); 
}
while (ascii_char != 0);
       //get the digits from the buffer and print the octal number
do
{
next_digit = (con_num[count] + '0');
cout << next_digit;
--count;
}
while (count > 0);
 
cout << "  in octal and  ";

       // convert octal number to decimal and let it print  
      
dec_num = 0;
dec_count = 1;
count = 1;
do
{
oct_num = (con_num[count] & 1);
if (oct_num == 1)
dec_num = (dec_num + dec_count);
dec_count = (dec_count + dec_count);
oct_num = (con_num[count] & 2);
if (oct_num == 2)
dec_num = (dec_num + dec_count);
dec_count = (dec_count + dec_count);
oct_num = (con_num[count] & 4);
if (oct_num == 4)
dec_num = (dec_num + dec_count);
dec_count = (dec_count + dec_count);

++count;
}
while (count <= 3);
cout << dec_num;
cout << "  in decimal.";

// prompt the operator for a 'y' or a 'n'  
cout << "\n\n       Try another character (y or n): ";

// if the answer is no return to the menu else ask for  
// another keyboard character  
ascii_char = cin.get ();
crlf_char = cin.get (); // get that crlf  
if (ascii_char == 'n')
return;
goto loop1;
}
// function to add, substract, multiply, or divide  
void arith_value ()
{       
char ascii_char;
char crlf_char;
float dec_numa;
float dec_numb;
float dec_num;
// get either a + b, a - b, a * b, or a / b from the operator  
loop1:  cout << "\n\n       Arithmetic operations\n";
cout << "       Examples: '8+2, 9-2, 7*7, or 8/2': ";

cin >> dec_numa >> ascii_char >> dec_numb;
// if it was a + b then add and thats the number a + b = c  
if (ascii_char == '+')

{
dec_num = (dec_numa + dec_numb);
cout << "\n\n       The answer is: ";
cout << dec_numa;
cout << " " << ascii_char << " ";
cout << dec_numb;
cout << " = ";
cout << dec_num;
}
// if it was a - b then subtract and thats the number a - b = c  

if (ascii_char == '-')
{
dec_num = (dec_numa - dec_numb);
cout << "\n\n       The answer is: ";
cout << dec_numa;
cout << " " << ascii_char << " ";
cout << dec_numb;
cout << " = ";
cout << dec_num;
}

// if it was a * b then multiply and thats the number a * b = c  
if (ascii_char == '*')
{
dec_num = (dec_numa * dec_numb);
cout << "\n\n       The answer is: ";
cout << dec_numa;
cout << " " << ascii_char << " ";
cout << dec_numb;
cout << " = ";
cout << dec_num;
}

// if it was a / b then  divide and thats the number a / b = c  
if (ascii_char == '/')
{
dec_num = (dec_numa / dec_numb);
cout << "\n\n       The answer is: ";
cout << dec_numa;
cout << " " << ascii_char << " ";
cout << dec_numb;
cout << " = ";
cout << dec_num;
}

cout << "\n\n       Try some more arithmatic 'y or n': ";
      
crlf_char = cin.get (); // get that crlf  
ascii_char = cin.get ();
// if the answer is no then return to menu else ask for next   
// number  
if (ascii_char == 'n')
return;
else goto loop1;
}

i read in here somewhere i dunno where or remmber but here is a c++ code for converting this to that and back again. not just trying to build up my post counts.

[Valik]

I recognize that code, I looked at that code 9 or 10 months ago when I was trying to figure out how to write a base converter. I didn't like how he did it. My converter can convert freely between base 2 (binary) and base 36 to any other base in that range. If Jon wants code that can do that, I can update mine as it's already using double's and only needs changed from using std::string to Variant or AString types. It needs updated anyway, when I wrote it, I barely knew what I was doing so I'm surprised it works at all (but it does)...

Mine's not too big, 2 functions. One to convert from any base to base 10, the other to convert from base 10 to anything else.

Edited January 25, 2004 by Valik

[GrahamS]

The code looks too complicated for me. There is inbuilt functionality within C++ to perform the conversions between octal, hexadecimal and decimal as well as perform a square root (actually there is also an inbuilt function in C and C++ called fabs which provides the absolute value of a floating point number).

Here is my simplified version of your code

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#include <iostream>
#include <iomanip>
#include <sstream>
#include <math.h>

static void sq_root ();
static void key_value ();
static std::string DecimalToOctal(long value);
static std::string DecimalToHex(long value);
static long OctalToDecimal(const std::string& value);
static long HexToDecimal(const std::string& value);
static void cdec_oct();
static void cdec_hex();
static void chex_dec();
static void coct_dec();
static void key_value();

int main()
{
    int dis_patch;
    // Repeat for ever

    while(true)
    {
        // print the menu  
        std::cout << "\n\n\n\n\n\n\n       MENU"
                   << "\n       ----"
                   << "\n\n       0 = Convert octal number to decimal."
                   << "\n\n       1 = Convert decimal number to octal."
                   << "\n\n       2 = Convert hex to decimal."
                   << "\n\n       3 = Convert decimal to hex."
                   << "\n\n       4 = Find the square root of a number."
                   << "\n\n       5 = Convert keyboard to decimal and octal."
                   << "\n\n       6 = Add, subtract, multiply, or divide."
                   << "\n\n       7 = Exit program."
                   << std::endl;    // Flushes the buffer

        // get menu selection from operator  
        std::cout << "\n\n       Enter menu number (0 - 7): ";
        std::cin >> dis_patch;
        switch(dis_patch)
        {
        case 0: coct_dec (); break;
        case 1: cdec_oct (); break;
        case 2: chex_dec (); break;
        case 3: cdec_hex (); break;
        case 4: sq_root ();  break;
        case 5: key_value (); break;
        //case 6: arith_value (); break;
        case 7: return 0;
        default:
            std::cout << "Input the correct menu number!" << std::endl;
        }
    }
    return 0;
}

// function to find the square root of a number  
static void sq_root ()
{
    float dec_num;
    do
    {
        std::cout << "\n\n       Input decimal number: ";
        std::cin >> dec_num;
        if (dec_num < 0)
            std::cout << "Cannot square root a negative number" << std::endl;
        else
        {
            std::cout << "\n       Square root is: " << sqrt(dec_num)
                      << "\n\n       Try another number (y or n): ";
        }
        std::cin.get(); // get and ignore that crlf  
    } while (std::cin.get() == 'y');
}

static std::string DecimalToOctal(long value)
{
    std::stringstream Temp;
    Temp << std::oct << value;
    return Temp.str();
}

static std::string DecimalToHex(long value)
{
    std::stringstream Temp;
    Temp << std::hex << value;
    return Temp.str();
}

static long OctalToDecimal(const std::string& value)
{
    long result;
    std::stringstream Temp(value);
    Temp >> std::oct >> result;
    return result;
}

static long HexToDecimal(const std::string& value)
{
    long result;
    std::stringstream Temp(value);
    Temp >> std::hex >> result;
    return result;
}

// function to convert decimal to octal  
static void cdec_oct ()
{
    long dec_num;
    do
    {
        std::cout << "\n\n       Enter decimal number: ";
        std::cin >> dec_num;

        std::cout << "\n       " << dec_num
                  << " in decimal is "
                  << DecimalToOctal(dec_num)
                  << " in octal."
                  << "\n\n       Try another number (y or n): ";
        std::cin.get(); // get and ignore that crlf  
    } while (std::cin.get() == 'y');
}

// function to convert decimal to hex
static void cdec_hex ()
{
    long dec_num;
    do
    {
        std::cout << "\n\n       Enter decimal number: ";
        std::cin >> dec_num;

        std::cout << "\n       " << dec_num
                  << " in decimal is "
                  << DecimalToHex(dec_num)
                  << " in hex."
                  << "\n\n       Try another number (y or n): ";
        std::cin.get(); // get and ignore that crlf  
    } while (std::cin.get() == 'y');
}

// This routine will convert a hex value to decimal  
static void chex_dec()
{       
    std::string input;
    do
    {
        std::cout << "\n\n       Enter hex number: ";
        std::cin >> input;
        std::cout << "\n       The answer is: " << HexToDecimal(input)
                  << "\n\n       Try another number 'y or n': ";
        std::cin.get(); // get and ignore that crlf  
    } while (std::cin.get() == 'y');
}

// This routine will convert an octal value to decimal  
static void coct_dec()
{       
    std::string input;
    do
    {
        std::cout << "\n\n       Enter oct number: ";
        std::cin >> input;
        std::cout << "\n       The answer is: " << OctalToDecimal(input)
                  << "\n\n       Try another number 'y or n': ";
        std::cin.get(); // get and ignore that crlf  
    } while (std::cin.get() == 'y');
}

// function to convert a keyboard character to its octal
// and then decimal value.  
static void key_value()
{
    char ascii_char;
    do
    {
        std::cout << "\n\n       Enter the Keyboard Character: ";
        std::cin >> ascii_char; 
        std::cin.get (); // get and ignore that crlf  
        std::cout << "\n\n       Keyboard Character:  '"
                  << ascii_char
                  << "'  "
                  << "is  "
                  << DecimalToOctal(ascii_char)
                  << "  in octal and  "
                  << static_cast<long>(ascii_char)
                  << "  in decimal."
                  << "\n\n       Try another number 'y or n': ";
        std::cin.get(); // get and ignore that crlf  
    } while (std::cin.get() == 'y');
}

The only major change I would make to function arith_value is to get rid of the goto statement.

[Valik]

The problem with those functions is that they are part of iostream which is part of the standard C++ library which Jon isn't using (Too much code bloat). Also, as you mentioned, you can only convert between a few specific types.